CN115073189A - Light castable with high thermal shock resistance for ladle cover and preparation method thereof - Google Patents

Abstract

A light castable with high thermal shock resistance for a ladle cover comprises the following raw materials in percentage by weight: high-alumina porous clinker or mullite porous clinker with the granularity of 0.1-8 mm: 40-65%, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 10-25%, 1-8% of kyanite with the granularity of less than or equal to 0.088mm, and clay powder with the granularity of less than or equal to 0.088 mm: 2-10%, alpha alumina powder with particle size less than or equal to 0.088 mm: 2-8%, calcium aluminate cement: 3-7%, the silicon powder with the particle size not more than 0.015mm is not more than 2%, the admixture accounts for 0.1-0.7% of the total weight of the raw materials, and the added water accounts for 3-6% of the total weight of the raw materials. According to the invention, the lightweight aggregate is selected, and the waste magnesium spinel brick is added as the aggregate, so that the thermal shock resistance of the castable is effectively enhanced, the thermal conductivity is reduced from not less than 0.8% to not more than 0.77%, the strength retention rate is not less than 80% after 5 times of water cooling, and the service cycle of the ladle cover is improved by 10-15% compared with the prior art.

Description

Light castable with high thermal shock resistance for ladle cover and preparation method thereof

Technical Field

The invention relates to a castable for a steelmaking part and a preparation method thereof, and particularly belongs to a light castable with high thermal shock resistance for a ladle cover and a preparation method thereof.

Background

The steel ladle or the ladle is an important tool for transferring the molten steel between steelmaking processes, the molten steel surface has larger heat loss to external radiation heat dissipation in the transferring process, if the steel ladle or the ladle is covered in the molten steel transferring process, the direct heat dissipation loss of the hot molten steel surface can be greatly reduced, so that the heat storage loss of the steel ladle in the molten steel transferring and placing process can be obviously reduced, and the temperature drop of the molten steel can be reduced by 15-20 ℃. The heat preservation performance and the service life of the ladle cover are two more key indexes, the good heat preservation performance of the ladle cover can effectively reduce the heat loss in the process of transferring and placing the molten steel and reduce the temperature drop of the molten steel, so that the production cost is reduced, and the turnover rate of the ladle cover and the ladle can be improved by prolonging the service life of the ladle cover.

The steel ladle cover is frequently covered and uncovered, and the thermal stress formed by a molten steel temperature field needs the refractory material of the steel ladle cover to have certain strength, and in addition, the steel ladle cover has larger temperature difference in the covering and uncovering processes, so that the refractory material of the steel ladle cover needs to have better thermal shock resistance. The refractory materials currently used for ladle lids fall into two categories, namely: one is a common high-aluminum casting material which has better strength and thermal shock resistance and long service life, but has high heat conductivity coefficient, poor heat preservation performance and large heat radiation loss in the molten steel transferring and placing process, and the other is a light heat preservation casting material which has low heat conductivity coefficient, good heat preservation performance, but relatively low strength and thermal shock resistance and far shorter service life than the former one.

After retrieval:

chinese patent publication No. CN 10920582 a discloses "a ladle heat-insulating castable and its application", which uses mullite, flint clay, andalusite as aggregate, clay powder, magnesite fine powder, alumina micropowder, and silica micropowder as matrix, and develops a castable suitable for ladle heat insulation, which can be used for a permanent layer, a furnace lining, and a ladle cover of a ladle, but is not a lightweight castable, and has a certain thermal shock resistance but a relatively high thermal conductivity coefficient.

A document of a test for preparing a lightweight castable of high-alumina hollow spheres, published in 2016 (8) 291 and 293, discloses the compactness, strength and phase composition of the high-alumina hollow spheres after heat treatment, and then the lightweight castable is prepared by respectively taking the high-alumina hollow spheres with the mass fractions of 30%, 35%, 40% and 45% as aggregates, and the influence of the addition of the hollow spheres on the performance of the lightweight castable is researched. The result shows that when the adding amount of the high-aluminum hollow spheres is 40%, the compactness and the strength of the light castable sample after drying and heat treatment are relatively optimal. The comparison document 2 mainly studies the influence of the addition of the hollow spheres on the strength of the castable, and does not relate to the slag resistance and the heat conductivity of the castable.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides the light castable material with high thermal shock resistance for the ladle cover and the preparation method thereof, wherein the light high-alumina porous clinker or the light mullite porous clinker is used as the aggregate, and the waste magnesium spinel brick is introduced as the aggregate, so that spinel is generated in situ in the castable material to form microcracks, thereby improving the thermal shock resistance of the castable material, effectively reducing the thermal conductivity coefficient and enhancing the normal temperature strength of the castable material.

The measures for realizing the aim are as follows:

a light castable with high thermal shock resistance for a ladle cover comprises the following raw materials in percentage by weight: high-alumina porous clinker or mullite porous clinker with the granularity of 0.1-8 mm: 40-65%, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 10-25%, 1-8% of kyanite with the granularity of less than or equal to 0.088mm, and clay powder with the granularity of less than or equal to 0.088 mm: 2-10%, alpha alumina powder with particle size less than or equal to 0.088 mm: 2-8%, calcium aluminate cement: 3-7%, the silicon powder with the particle size not more than 0.015mm is not more than 2%, the admixture accounts for 0.1-0.7% of the total weight of the raw materials, and the added water accounts for 3-6% of the total weight of the raw materials.

Preferably: the weight percentage content of the high-alumina porous clinker or the mullite porous clinker with the granularity of 0.1-8 mm is 48-61%.

Preferably: the weight percentage content of the waste magnesium spinel brick with the granularity of 0.1-8 mm is 12.5-22%.

Preferably: the additive accounts for 0.2-0.65% of the total weight of the raw materials.

Preferably: the additive consists of a cementing agent and an explosion-proof organic fiber; 70-90% of cementing agent, and the balance of explosion-proof organic fiber;

the cementing agent is sodium tripolyphosphate or sodium hexametaphosphate; the explosion-proof organic fiber is polypropylene fiber or polyethylene fiber or the combination of the two.

It is characterized in that: in the waste magnesium spinel brick with the granularity of 0.1-8 mm: the granularity is more than 3 and less than or equal to 8mm, and the granularity accounts for 20-40%; the granularity is more than 1 and less than or equal to 3mm, and accounts for 30-50 percent; the granularity is more than 0.1 and less than or equal to 1mm, and accounts for 20-40%.

A preparation method of a light castable with high thermal shock resistance for a ladle cover comprises the following steps:

1) according to the addition proportion: high-alumina porous clinker or mullite porous clinker with the granularity of 0.1-8 mm: 40-65%, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 10-25%, 1-8% of kyanite with the granularity of less than or equal to 0.088mm, and clay powder with the granularity of less than or equal to 0.088 mm: 2-10%, alpha alumina powder with particle size less than or equal to 0.088 mm: 2-8%, calcium aluminate cement: 3-7% of silicon powder with the granularity less than or equal to 0.015mm and less than or equal to 2% of silicon powder are mixed;

2) mixing the following additives: 0.1-0.7% of the raw materials are added and uniformly stirred;

3) use of:

A. when the water-soluble paint is used in time, adding additional water and stirring uniformly for use;

B. when the mixture is not used in time, the mixture obtained in the step 2) is bagged for later use, and water is added and stirred uniformly when the mixture is used.

The principles of selection and weight percentage control of each component in the castable of the invention are as follows:

the light high-aluminum porous clinker or the light mullite porous clinker is porous or honeycomb-shaped, has small bulk density and high particle strength, can effectively reduce the thermal conductivity of the castable, is added with a proper amount of waste magnesium spinel bricks, and is characterized in that:

firstly, the waste is recycled, the waste is changed into valuable, and the waste magnesium spinel brick is comprehensively utilized;

secondly, the magnesia-alumina spinel can react with alumina to generate in-situ, and microcracks are formed in the castable so as to improve the thermal shock resistance of the castable, but the spinel generated in-situ cannot be excessive, namely the total content of the spinel is controlled to be 15-20%, the spinel generated in-situ accounts for 60-80% of the total content of the spinel, otherwise, the strength of the castable is reduced;

and a spinel layer is formed in the casting material, so that the strength of the casting material can be improved.

A certain amount of kyanite is added to be mullite at high temperature, and the thermal shock stability of the castable can be enhanced along with certain volume expansion, so that the shrinkage of the lightweight aggregate at high temperature can be effectively compensated, and the linear expansion rate of the castable is controlled; the addition of the clay powder is beneficial to uniformly mixing the aggregate and the fine powder to form compact accumulation, the explosion-proof organic fiber has the function of facilitating the discharge of water and preventing the local bursting of the material, and the explosion-proof organic fiber is melted in the castable at high temperature to form partial closed-cell microcracks, so that the thermal conductivity of the castable can be reduced.

Experiments prove that the performance of the castable is greatly influenced by carrying out granularity grading on aggregate in the castable, continuous particle compact accumulation is formed by strictly controlling the total weight percentage of the lightweight high-alumina porous clinker or the lightweight mullite porous clinker, the waste magnesium spinel brick, the kyanite, the clay powder and various fine powders, the densification of the castable is realized to the maximum extent, and the castable has higher normal temperature strength, lower thermal conductivity and better thermal shock resistance.

Description of the drawings: the invention is not limited to use with ladle lids.

Compared with the prior art, the lightweight aggregate is reasonably selected, the waste magnesium spinel brick is added as the aggregate, the thermal shock resistance of the castable is effectively enhanced, the thermal conductivity of the castable is reduced from not less than 0.8% to not more than 0.70%, the heat insulation performance of the ladle cover is enhanced, the temperature of molten steel can be reduced by 2-3 ℃, the strength retention rate is not less than 80% after 5 times of water cooling, and the service cycle of the ladle cover is improved to not less than 418 furnaces compared with the current about 380 furnaces, namely the improvement rate is 10-15%.

Detailed Description

The present invention is described in detail below

Table 1 shows the physical properties of the samples in the examples of the present invention.

Example 1

A light castable with high thermal shock resistance for a ladle cover comprises the following raw materials in percentage by weight: mullite porous clinker with the granularity of 0.1-8 mm: 55 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 25 percent, 4 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 6 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 4%, calcium aluminate cement: 5 percent of silicon micropowder with the granularity less than or equal to 0.015mm, and an additive accounting for 0.3 percent of the total weight of the raw materials, wherein the additive comprises the following components in percentage by weight: 0.2 percent of sodium tripolyphosphate, 0.1 percent of explosion-proof organic fiber and 4 percent of added water in the total weight of the raw materials.

In 55% of the light mullite porous clinker, the granularity is more than 3mm and less than or equal to 8mm, and accounts for 35%; the granularity is more than 1 and less than or equal to 3mm, and the granularity accounts for 35 percent; the granularity is more than 0.1 and less than or equal to 1mm, and accounts for 30 percent;

in 25 percent of the waste magnesium spinel bricks, the granularity of more than 3mm and less than or equal to 8mm accounts for 30 percent; the granularity is more than 1mm and less than or equal to 3mm, and accounts for 30 percent; the granularity is more than 0.1mm and less than or equal to 1mm, and accounts for 40 percent.

The preparation method comprises the following steps:

1) according to the addition proportion: mullite porous clinker with the granularity of 0.1-8 mm: 55 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 25 percent, 4 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 6 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 4%, calcium aluminate cement: 5 percent of silicon micro powder with the granularity less than or equal to 0.015mm is mixed with the mixture;

2) mixing the following additives: 0.3 percent of the mixture is added and stirred evenly;

3) use of: because the raw materials are used in time, additional water accounting for 4 percent of the total weight of the raw materials is added and uniformly stirred for use, and a vibrating rod is inserted for vibration in the stirring process.

Preparing a castable into a strip sample of 40 multiplied by 160mm, carrying out heat treatment at 110 ℃ for 24 hours after molding and curing to prepare a sample, and then carrying out heat treatment on the sample at 1400 ℃ for 3 hours, wherein the detection results are shown in Table 1.

Example 2

A light castable with high thermal shock resistance for a ladle cover comprises the following raw materials in percentage by weight: mullite porous clinker with the granularity of 0.1-8 mm: 60 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 20 percent of kyanite with the granularity of less than or equal to 0.088mm, 5 percent of clay powder with the granularity of less than or equal to 0.088 mm: 5 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 3%, calcium aluminate cement: 6 percent of silicon micropowder with the granularity less than or equal to 0.015mm, and an additive accounting for 0.3 percent of the total weight of the raw materials, wherein in the additive: 0.2 percent of sodium tripolyphosphate, 0.1 percent of explosion-proof organic fiber and 6 percent of added water in the total weight of the raw materials.

In 55% of the light mullite porous clinker, the granularity of more than 3mm is less than or equal to 8mm and accounts for 40%; the granularity is more than 1 and less than or equal to 3mm, and accounts for 30 percent; the granularity is more than 0.1 and less than or equal to 1mm, and accounts for 30 percent;

in 25 percent of the waste magnesium spinel bricks, the granularity of more than 3mm and less than or equal to 8mm accounts for 40 percent; the granularity is more than 1mm and less than or equal to 3mm, and accounts for 30 percent; the granularity is more than 0.1mm and less than or equal to 1mm, and accounts for 30 percent.

The preparation method comprises the following steps:

1) according to the addition proportion: mullite porous clinker with the granularity of 0.1-8 mm: 60 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 20 percent, kyanite with the granularity less than or equal to 0.088mm accounts for 5 percent, and clay powder with the granularity less than or equal to 0.088 mm: 5 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 3%, calcium aluminate cement: 6 percent of silicon micro powder with the granularity less than or equal to 0.015mm is mixed with the mixture;

2) mixing the following additives: 0.3 percent of the mixture is added and stirred evenly;

3) use of: because the raw materials are used in time, added water accounting for 6 percent of the total weight of the raw materials is added and uniformly stirred for use, and a vibrating rod is inserted for vibration in the stirring process.

Preparing a castable into a strip sample of 40 multiplied by 160mm, carrying out heat treatment at 110 ℃ for 24 hours after molding and curing to prepare a sample, and then carrying out heat treatment on the sample at 1400 ℃ for 3 hours, wherein the detection results are shown in Table 1.

Example 3

A light castable with high thermal shock resistance for a ladle cover comprises the following raw materials in percentage by weight: mullite porous clinker with the granularity of 0.1-8 mm: 58 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 18 percent, 6 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 5 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 5%, calcium aluminate cement: 6 percent of silicon micropowder with the granularity less than or equal to 0.015mm and an additive accounting for 0.3 percent of the total weight of the raw materials, wherein the additive comprises the following components in percentage by weight: 0.2 percent of sodium tripolyphosphate, 0.1 percent of explosion-proof organic fiber and 5 percent of added water in the total weight of the raw materials.

In 55% of the light mullite porous clinker, the granularity is more than 3mm and less than or equal to 8mm, and the light mullite porous clinker accounts for 30%; the granularity is more than 1 and less than or equal to 3mm, and accounts for 40 percent; the granularity is more than 0.1 and less than or equal to 1mm, and accounts for 30 percent;

in 25 percent of the waste magnesium spinel bricks, the granularity of more than 3mm and less than or equal to 8mm accounts for 30 percent; the granularity is more than 1mm and less than or equal to 3mm, and accounts for 40 percent; the granularity of more than 0.1mm and less than or equal to 1mm accounts for 30 percent.

The preparation method comprises the following steps:

1) according to the addition proportion: mullite porous clinker with the granularity of 0.1-8 mm: 58 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 18 percent, 6 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 5 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 5%, calcium aluminate cement: 6 percent of silicon micro powder with the granularity less than or equal to 0.015mm is mixed with the mixture of 2 percent;

2) mixing the following additives: 0.3 percent of the mixture is added and stirred evenly;

3) use of: because the raw materials are used in time, the external water accounting for 5 percent of the total weight of the raw materials is added and uniformly stirred for use, and a vibrating rod is inserted for vibration in the stirring process.

Preparing a castable into a strip sample of 40 multiplied by 160mm, carrying out heat treatment at 110 ℃ for 24 hours after molding and curing to prepare a sample, and then carrying out heat treatment on the sample at 1400 ℃ for 3 hours, wherein the detection results are shown in Table 1.

Example 4

A light castable with high thermal shock resistance for a ladle cover comprises the following raw materials in percentage by weight: mullite porous clinker with granularity of 0.1-8 mm: 65 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 15 percent, 5 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 5 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 3.5%, calcium aluminate cement: 5 percent of silicon micropowder with the granularity less than or equal to 0.015mm, and an additive accounting for 0.4 percent of the total weight of the raw materials, wherein the additive comprises the following components in percentage by weight: 0.3 percent of sodium tripolyphosphate, 0.1 percent of explosion-proof organic fiber and 5 percent of added water in the total weight of the raw materials.

In 65% of the light mullite porous clinker, the granularity is more than 3mm and less than or equal to 8mm, and the light mullite porous clinker accounts for 45%; the granularity is more than 1 and less than or equal to 3mm, and the granularity accounts for 35 percent; the granularity is more than 0.1 and less than or equal to 1mm, and accounts for 20 percent;

in 15 percent of the waste magnesium spinel bricks, the granularity is more than 3mm and less than or equal to 8mm, and accounts for 45 percent; the granularity is more than 1mm and less than or equal to 3mm, and accounts for 35 percent; the granularity is more than 0.1mm and less than or equal to 1mm, and accounts for 20 percent.

The preparation method comprises the following steps:

1) according to the addition proportion: mullite porous clinker with the granularity of 0.1-8 mm: 65 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 15 percent, 5 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 5 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 3.5%, calcium aluminate cement: 5 percent of silicon micro powder with the granularity less than or equal to 0.015mm is mixed with 1.5 percent of the silicon micro powder;

2) mixing the following additives: 0.4 percent of the mixture is added and stirred evenly;

3) use of: because the raw materials are used in time, the external water accounting for 5 percent of the total weight of the raw materials is added and uniformly stirred for use, and a vibrating rod is inserted for vibration in the stirring process.

Preparing a castable into a strip sample of 40 multiplied by 160mm, performing heat treatment at 110 ℃ for 24 hours after molding and maintenance, preparing a sample, and performing heat treatment on the sample at 1400 ℃ for 3 hours, wherein the detection results are shown in table 1.

Example 5

A light castable with high thermal shock resistance for a ladle cover comprises the following raw materials in percentage by weight: mullite porous clinker with the granularity of 0.1-8 mm: 45 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 25 percent, 8 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 10 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 6%, calcium aluminate cement: 5 percent of silicon micropowder with the granularity less than or equal to 0.015mm, and an additive accounting for 0.6 percent of the total weight of the raw materials, wherein the additive comprises the following components in percentage by weight: 0.5 percent of sodium tripolyphosphate, 0.1 percent of explosion-proof organic fiber and 5 percent of added water in the total weight of the raw materials.

In 45 percent of the lightweight mullite porous clinker, the granularity of more than 3mm and less than or equal to 8mm accounts for 30 percent; the granularity is more than 1 and less than or equal to 3mm, and accounts for 45 percent; the granularity is more than 0.1 and less than or equal to 1mm, and accounts for 25 percent;

in 15 percent of the waste magnesium spinel bricks, the granularity is more than 3mm and less than or equal to 8mm, and accounts for 30 percent; the granularity is more than 1mm and less than or equal to 3mm, and accounts for 45 percent; the granularity is more than 0.1mm and less than or equal to 1mm, and accounts for 25 percent.

The preparation method comprises the following steps:

1) according to the addition proportion: mullite porous clinker with the granularity of 0.1-8 mm: 45 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 25 percent, 8 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 10 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 6%, calcium aluminate cement: 5 percent of silicon micro powder with the granularity less than or equal to 0.015mm is mixed with the mixture;

2) mixing the following additives: 0.6 percent of the mixture is added and stirred evenly;

3) use of: because the raw materials are used in time, the external water accounting for 5 percent of the total weight of the raw materials is added and uniformly stirred for use, and a vibrating rod is inserted for vibration in the stirring process.

Preparing a castable into a strip sample of 40 multiplied by 160mm, carrying out heat treatment at 110 ℃ for 24 hours after molding and curing to prepare a sample, and then carrying out heat treatment on the sample at 1400 ℃ for 3 hours, wherein the detection results are shown in Table 1.

Example 6

A light castable with high thermal shock resistance for a ladle cover comprises the following raw materials in percentage by weight: mullite porous clinker with the granularity of 0.1-8 mm: 59 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 17 percent, 6 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 8 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 4%, calcium aluminate cement: 5 percent of silicon micropowder with the granularity less than or equal to 0.015mm, and an additive accounting for 0.5 percent of the total weight of the raw materials, wherein the additive comprises the following components in percentage by weight: 0.4 percent of sodium tripolyphosphate, 0.1 percent of explosion-proof organic fiber and 5 percent of added water in the total weight of the raw materials.

In 59 percent of the lightweight mullite porous clinker, the granularity is more than 3mm and less than or equal to 8mm, and the lightweight mullite porous clinker accounts for 24 percent; the granularity is more than 1 and less than or equal to 3mm, and accounts for 48 percent; the granularity is more than 0.1 and less than or equal to 1mm, and the granularity accounts for 28 percent;

in 15 percent of the waste magnesium spinel bricks, the granularity is more than 3mm and less than or equal to 8mm, and the waste magnesium spinel bricks account for 24 percent; the granularity is more than 1mm and less than or equal to 3mm, and the granularity accounts for 48 percent; the granularity is more than 0.1mm and less than or equal to 1mm, and the granularity accounts for 28 percent.

The preparation method comprises the following steps:

1) according to the addition proportion: mullite porous clinker with the granularity of 0.1-8 mm: 59 percent, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 17 percent, 6 percent of kyanite with the granularity less than or equal to 0.088mm, and clay powder with the granularity less than or equal to 0.088 mm: 8 percent of alpha alumina powder with the granularity less than or equal to 0.088 mm: 4%, calcium aluminate cement: 5 percent of silicon micro powder with the granularity less than or equal to 0.015mm is mixed with the mixture;

2) mixing the following additives: 0.5 percent of the mixture is added and stirred evenly;

3) use of: because the raw materials are used in time, the external water accounting for 5 percent of the total weight of the raw materials is added and uniformly stirred for use, and a vibrating rod is inserted for vibration in the stirring process.

Preparing a castable into a strip sample of 40 multiplied by 160mm, carrying out heat treatment at 110 ℃ for 24 hours after molding and curing to prepare a sample, and then carrying out heat treatment on the sample at 1400 ℃ for 3 hours, wherein the detection results are shown in Table 1.

TABLE 1 physical Properties of samples of the examples of the invention

	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6
							Bulk density/g.cm -3	1.80	1.71	1.63	1.61	1.78	1.68
Apparent porosity/%	29.1	27.8	30.7	31.4	28.6	33.2
							Linear rate of change/%)	0.38	0.33	0.40	0.41	0.38	0.32
Normal temperature rupture strength/MPa	8.5	8.4	8.6	8.8	8.7	8.2
							Normal temperature compressive strength/Mpa	64.8	63.9	62.2	63.5	63.8	62.3
The heat conductivity coefficient W/(m.K) is 1000 DEG C	0.68	0.56	0.61	0.64	0.66	0.58
							Strength retention after 5 water-cooling%	82	83	81	84	82	82

The physical properties of the examples are shown in Table 1, the thermal conductivity coefficient of the examples is between 0.56 and 0.68W/(mK), the thermal conductivity coefficient is remarkably reduced compared with that of a common high-aluminum castable (1.6 to 1.8W/(mK)) and a common light castable (0.8 to 1.0W/(mK)), the strength retention rate of the common light castable after being cooled by water for 5 times is about 60 to 70 percent, and the thermal shock resistance of the invention is greatly improved and is not lower than 80 percent. Through trial, compared with the prior use of the common light castable, the temperature drop of the ladle heat transfer is reduced by 2-3 ℃, the service life of the ladle cover is prolonged from 380 furnaces to at least 418 furnaces, and is increased by 10% or more.

The present embodiments are merely preferred examples, and are not intended to limit the scope of the present invention.

Claims (7)

1. A light castable with high thermal shock resistance for a ladle cover comprises the following raw materials in percentage by weight: high-alumina porous clinker or mullite porous clinker with the granularity of 0.1-8 mm: 40-65%, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 10-25%, 1-8% of kyanite with the granularity of less than or equal to 0.088mm, and clay powder with the granularity of less than or equal to 0.088 mm: 2-10%, alpha alumina powder with particle size less than or equal to 0.088 mm: 2-8%, calcium aluminate cement: 3-7%, the silicon powder with the particle size not more than 0.015mm is not more than 2%, the admixture accounts for 0.1-0.7% of the total weight of the raw materials, and the added water accounts for 3-6% of the total weight of the raw materials.

2. The lightweight castable material with high thermal shock resistance for the ladle cover according to claim 1, wherein: the weight percentage content of the high-alumina porous clinker or the mullite porous clinker with the granularity of 0.1-8 mm is 48-61%.

3. The lightweight castable with high thermal shock resistance for ladle covers according to claim 1, wherein: the weight percentage content of the waste magnesium spinel brick with the granularity of 0.1-8 mm is 12.5-22%.

4. The lightweight castable material with high thermal shock resistance for the ladle cover according to claim 1, wherein: the additive accounts for 0.2-0.65% of the total weight of the raw materials.

5. The lightweight castable with high thermal shock resistance for the ladle cover according to claim 1 or 4, wherein: the additive consists of a cementing agent and an explosion-proof organic fiber; 70-90% of cementing agent, and the balance of explosion-proof organic fiber; the cementing agent is sodium tripolyphosphate or sodium hexametaphosphate; the explosion-proof organic fiber is polypropylene fiber or polyethylene fiber or the combination of the two.

6. The lightweight castable for ladle covers with high thermal shock resistance as claimed in claim 1 or 2, wherein: in the waste magnesium spinel brick with the granularity of 0.1-8 mm: the granularity is more than 3 and less than or equal to 8mm, and the granularity accounts for 20-40%; the granularity is more than 1 and less than or equal to 3mm, and accounts for 30-50 percent; the granularity is more than 0.1 and less than or equal to 1mm, and accounts for 20-40%.

7. The preparation method of the light castable with high thermal shock resistance for the ladle cover as claimed in claim 1, comprising the steps of:

1) according to the addition proportion: high-alumina porous clinker or mullite porous clinker with the granularity of 0.1-8 mm: 40-65%, and the particle size of the waste magnesium spinel brick is 0.1-8 mm: 10-25%, 1-8% of kyanite with the granularity of less than or equal to 0.088mm, and clay powder with the granularity of less than or equal to 0.088 mm: 2-10%, alpha alumina powder with particle size less than or equal to 0.088 mm: 2-8%, calcium aluminate cement: 3-7% of silicon powder with the granularity less than or equal to 0.015mm and less than or equal to 2% of silicon powder are mixed;

2) mixing the following additives: 0.1-0.7% of the raw materials are added and uniformly stirred;

3) use of:

A. when the water-soluble paint is used in time, adding additional water and stirring uniformly for use;

B. when the mixture is not used in time, the mixture obtained in the step 2) is bagged for later use, and water is added and stirred uniformly when the mixture is used.